An Opportunistic Void Avoidance Routing Protocol for Underwater Sensor Networks

An Underwater Sensor Network (UWSN) has many unique features that makes it different from terrestrial network. This includes lower bandwidth, longer propagation delay, dynamic topology, high error rate, and energy constraint. To overcome the limitations of such an environment, opportunistic routing has recently attracted much attention due to its ability to improve the performance of UWSNs in terms of packet delivery ratio and energy saving. With the aid of opportunistic data routing, underwater sensors can collaboratively route a packet towards the destination which is a more adequate approach for sparse and lossy channels. In this paper, we propose a new routing protocol, called Opportunistic Void Avoidance Routing (OVAR), to address the void problem and high bit error rate without relying on any positioning system. OVAR is able to efficiently bypass all kinds of void areas with the lowest possible cost (including energy and delay) while prioritising the group of candidate nodes with the highest packet advancement. Given the density of neighbours (sparse or dense), each forwarding node is able to hold a trade-off between packet advancement and energy consumption by adjusting the number of nodes in its forwarding set. OVAR is also able to select the forwarding set in any direction from the sender without including any hidden node. The results of our extensive simulation study show that OVAR outperforms other protocols in terms of packet delivery ratio, energy consumption, and average end-to-end delay.